Dc SQUID based on a three-band superconductor with broken time-reversal symmetry

Abstract

The behavior of a dc SQUID, based on a dirty point contacts between a single-band and three-band superconductor with broken time-reversal symmetry is investigated. Using earlier obtained results for Josephson effects in such systems new features in characteristics of a dc SQUID are revealed. It is shown that in the case of a BTRS (broken time-reversal symmetry) three-band superconductor for the applied external magnetic flux, which is divisible by the half-integer flux, strong degeneracy of ground states of a dc SQUID is taken place. This can lead to the appearance of possible multi-hysteresis loops on a dependence of a total flux in the dc SQUID from the externally applied flux. The number of these loops depends on the position of ground states of a three-band superconductor. Also it is found that dependencies of a critical current on applied magnetic flux can have complicated multi-periodic forms, which are differ from strictly periodic characteristics for conventional dc SQUIDs and Fraunhofer patterns for Josephson contacts in the external magnetic field. PACS number(s): 74.50.+r, 85.25.Dq

Proximity and Josephson effects in microstructures based on multiband superconductors (Review Article)

“…This has first been shown theoretically in Ref. 119, in which a dc SQUID with diffusion microcontacts between single-band and three-band superconductors has been considered. Figure 29 shows the contour maps of the energy as a function of the phase differences v 1 and v 2 at the junctions for an ordinary dc SQUID formed by s-wave superconductors [ Figs.…”

s+is superconductivity with incipient bands: Doping dependence and STM signatures

“…While the first report 60 provided no evidence, recent results 61 are consistent with s + is state at x = 0.73, close to the region where the Lifshitz transition is considered to occur. Other possible experimental signatures of s + is superconductivity have also been suggested 62,63 . Crucially, the data presented in 61 encourages one to consider s + is state in more detail with application to Ba 1−x K x Fe 2 As 2 and propose complementary techniques to study its properties.…”

Josephson systems based on ballistic point contacts between single-band and multi-band superconductors

“…(7) and (8) the total current flowing through the Josephson junction between tw s-wave single-band superconductors, is [30] sin sgn cos 2 2…”

“…27 and references therein). While several technologies have already been proposed for the detection of potential BTRS in iron-based superconductors [28][29][30][31] currently there is no strong experimental evidence for the existence of this phenomenon in iron-based superconductors.…”

“…Previously, we investigated the Josephson effect [32] and the behavior of a dc SQUID with Josephson point contacts between an s-wave superconductor and a three-band isotropic superconductor in the dirty limit [30] We have revealed the unusual dependence of the critical current on the external magnetic flux and demonstrated the possibility of appearance of multihysteresis loops in the dependence of the total flux on the external magnetic flux. It was found that all these features of Josephson systems are associated with BTRS.…”